import java.util.LinkedList;
import java.util.Queue;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User:何人亮
 * Date:2024-08-18
 * 14:47
 */
public class BinaryTree {
    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }

    public static TreeNode head;

    /**
     * 创建一棵二叉树 返回这棵树的根节点
     *
     * @return
     */
    public TreeNode createTree() {
        TreeNode A=new TreeNode('A');
        head=A;
        TreeNode B=new TreeNode('B');
        TreeNode C=new TreeNode('C');
        TreeNode D=new TreeNode('D');
        TreeNode E=new TreeNode('E');
        TreeNode F=new TreeNode('F');
        TreeNode G=new TreeNode('G');
        A.left=B;
        A.right=C;
        B.left=D;
        B.right=E;
        C.left=G;

        return A;
    }

    // 前序遍历
    public void preOrder(TreeNode root) {
        if(root==null){
            return ;
        }
        System.out.print(root.val+" ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if(root==null) {
            return;
        }
        inOrder(root.left);
        System.out.print(root.val+" ");
        inOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
        if(root==null){
            return ;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val+" ");
    }

    public static int nodeSize;

    /**
     * 获取树中节点的个数：遍历思路
     */
    void size(TreeNode root) {
        if(root==null){
            return ;
        }
        nodeSize++;
        size(root.left);
        size(root.right);

    }

    /**
     * 获取节点的个数：子问题的思路
     *
     * @param root
     * @return
     */
    int size2(TreeNode root) {
        if(root==null){
            return 0;
        }
        return size2(root.right)+size2(root.left)+1;
    }


    /*
     获取叶子节点的个数：遍历思路
     */
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if(root==null){
            return ;
        }
        if(root.left==null&&root.right==null){
            leafSize++;
        }
        getLeafNodeCount1(root.right);
        getLeafNodeCount1(root.left);
    }

    /*
     获取叶子节点的个数：子问题
     */
    int getLeafNodeCount2(TreeNode root) {
        if(root==null){
            return 0;
        }
        if(root.left==null&&root.right==null){
            return 1;
        }

        return getLeafNodeCount2(root.left)+getLeafNodeCount2(root.right);
    }

    /*
    获取第K层节点的个数
     */
    int getKLevelNodeCount(TreeNode root, int k) {

       if(root==null){
           return 0;
       }
        if(k==1){
            return 1;
        }
        return getKLevelNodeCount(root.left,k-1)+
        getKLevelNodeCount(root.right,k-1);
    }

    /*
     获取二叉树的高度
     时间复杂度：O(N)
     */
    int getHeight(TreeNode root) {
        if(root==null){
            return 0;
        }
        int leftL=getHeight(root.left);
        int rightL=getHeight(root.right);
       // return right>left?right+1:left+1;
        return Math.max(rightL,leftL)+1;
    }


    // 检测值为value的元素是否存在
    TreeNode find(TreeNode root, char val) {
        if(root==null){
            return null;
        }
        if(root.val==val){
            return root;
        }
        TreeNode leftT=find(root.left,val);
        if(leftT!=null) {
            return leftT;
        }
        TreeNode rightT=find(root.right,val);
        if(rightT!=null){
            return rightT;
        }
        return null;
    }

    //层序遍历
    void levelOrder(TreeNode root) {
        if(root==null){
            return ;
        }
        Queue<TreeNode> queue=new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()){
            TreeNode cur= queue.poll();
            System.out.println(cur.val+" ");
            if(cur.left!=null){
                queue.offer(cur.left);
            }
            if(cur.right!=null){
                queue.offer(cur.right);
            }
        }
        System.out.println();
    }


    // 判断一棵树是不是完全二叉树
    public boolean isBalanced(TreeNode root) {
        if(root==null){
            return true;
        }
        int leftL=getHeight(root.left);
        int rightL=getHeight(root.right);
        if(leftL-rightL>1||rightL-leftL>1){
            return false;
        }
        return isBalanced(root.left)&&isBalanced(root.right);//时间复杂度O(n^2)
        //return getHeight2>0  时间复杂度O(n)
    }
    int getHeight2(TreeNode root) {
        if(root==null){
            return 0;
        }
        int leftL=getHeight(root.left);
        if(leftL<0){
            return -1;
        }
        int rightL=getHeight(root.right);
        // return right>left?right+1:left+1;
        if(rightL>0&&Math.abs(rightL-leftL)<2){
            return Math.max(leftL,rightL)+1;
        }else {
            return -1;
        }
    }

}
